The invention relates to a gearbox with a shaft bearing which is accommodated in a bearing eye adjacent to an assembly opening. For assembly reasons, the bearing eye is slotted towards the assembly opening. A cap is provided which closes the bearing bore and the assembly opening towards the outside. Known examples of this type of gearbox are shown in the German Patent Specifications 591 653 and 41 21 299. The slot in the bearing eye forming the bearing bore has the disadvantage that the bearing is unsupported over a part of its periphery. The intention of the invention is to avoid this disadvantage and permit wider slotting than has previously been possible, taking account of the life of the bearing.
This objective is achieved, according to the invention, by the cap adjacent to the bearing eye containing a bore which accommodates the bearing over the major part of its axial extent. In this arrangement, the bore in the bearing eye is essentially used for centering the bearing and only to a limited extent for supporting it. The bearing is, rather, supported by the bore in the cap. This bore obtains its correct location by being centered by the bearing from the bearing bore of the bearing eye before the cap is bolted to the gearbox casing, so that it can transmit force.
It is, in fact, known (EP-A 69215) to center the cap of an assembly opening not only by arranging the bearing adjacent to the assembly opening in the bearing eye but also by its protruding a little into a corresponding bore in the cap. In the known configuration, however, the bearing only engages sufficiently far in the cap bore for the centering purpose to be achieved. Support of the bearing by the cap is not envisaged and, in the case of a support length limited to the edge region of the bearing, is not possible either because such support is mainly demanded in the central region of the bearing. In the known configuration, the support takes place exclusively in the bearing eye. The invention reverses these relationships by limiting the bearing eye to the centering function and allocating the support function to the cap. Since the bearing is supported by the cap over its complete periphery and the centering function of the bearing eye is not impaired by the slotting, the invention permits the bearing eye to be slotted without impairment and, in fact, over a larger part of the periphery than was previously conceivable.
Assembly problems can also arise where the gearbox casing contains an intermediate wall for supporting the output shaft and possibly further shafts. In this case, it is generally necessary to provide an additional assembly opening for inserting the output wheel in the region between the output-end wall of the gearbox casing and the intermediate wall. The invention avoids this disadvantage by lopping the intermediate wall in the region of the bearing accommodation bore provided for the support of the output shaft and by specifying a certain dimensioning rule for the free width of the casing between the intermediate wall and the casing wall opposite to it. Although this width must have somewhat larger dimensions than those of known gearbox casings, which contain an additional assembly opening, it is a surprising fact that, when this rule is observed, this width can be limited to such an extent that the extra outlay for it is often less than that required for the arrangement of an additional assembly opening. In this arrangement, the edge bounding the intermediate wall extends through the bearing accommodation bore for the support of the output shaft so that this bore is open towards the opposite casing wall and a support element, which supports the bearing in the region of this opening and which can be formed by a support ring, must be provided. In this way, the widening of the free assembly space can take place by raising the casing wall opposite to the intermediate wall by only a small amount. This, however, only applies if the dimensioning rule mentioned above is observed. This rule also takes into consideration the width of the installation space for the output wheel between the intermediate wall and the output-end casing wall. The output wheel can be introduced through the free assembly space created in this way by first inserting it at right angles to its assembly position and then gradually pivoting it into the assembly position with one end surface sliding on the edge of the intermediate wall.
Generally speaking, the upper boundary of the intermediate wall in the direction of the free assembly space will be selected to be as high as possible in order to improve the stiffening of the casing effected by the intermediate wall. The upper edge of the intermediate wall then coincides with the edge over which the output wheel slides while it is being pivoted during assembly. This edge extends over at least that length which corresponds to the end-face diameter of the output wheel.
The extension of the gearbox casing on the side opposite to the intermediate wall can become smaller as the free space between the intermediate wall and the output-end wall of the casing becomes greater. The main interest here is in that region of the inner surface of the output-end casing wall along which the outermost edge of the output wheel slides at a pivoting angle between about 35 and 55 degrees. This is, as a rule, the height region in which the output shaft is located. In order to increase the free space in this region, it is possible to make provision for the inside of the output-end casing wall to have a corresponding recess in the height region of the output shaft. In order to increase the free assembly space, furthermore, the edge of the intermediate wall can be chamfered towards the output end. If the terms "top" and "height" are used in this connection, this is based on the idea that the output shaft extends horizontally, that the intermediate wall is arranged in the region of the gearbox near the bottom and that its upper edge extends approximately horizontally, the opposite casing wall being formed by the top of the casing. It is obvious that the gearbox can also have a different orientation.